The Clinical Exposure Facility consists of a human exposure chamber and supporting areas located on the first floor of the Medical Research Facility. The exposure chamber is a single stainless-steel-paneled room (12? x 12? x 8?) with a ventilation system solely dedicated to the chamber. Airflow conditions are set for high flow with the ability to obtain a wide-variety of temperature and relative humidity conditions. The quality of the air is carefully controlled before being introduced to the chamber. The chamber also contains a reclining chair for subjects, a treadmill for subject exercise, and a full body plethysmograph. A full range of analyzers is available for evaluating pulmonary function as well as characterizing dry aerosols, wet aerosols, particle sizes, and ozone concentrations. The facility also includes a Clinical Bronchoscopy Suite which is part of the University of Iowa Hospitals and Clinics located adjacent to the General Clinical Research Center. Included within this facility is the Laboratory Physiologic Imaging. This laboratory offers a full range of state of the art imaging and analysis capabilities regarding changes in thoracic contents and lung organization. The overall goal of the Clinical Exposure Facility is to provide a high quality exposure facility to promote clinical research studies on relevant agricultural and rural exposures and their health effects. The specific aims of the facility include the following: 1. To perform acute human exposures to dry aerosols, gases, nebulized solutions, and combined exposures under rigidly controlled conditions which are safe for both research subjects and research personnel. 2. To rigorously control (concentration and size), monitor, and quantify exposures throughout the studies. 3. To rigorously control, monitor, and quantify environmental (non exposure) conditions throughout the studies. 4. To closely monitor pulmonary physiologic responses prior to, during, and after experimental exposure studies. 5. To obtain biological samples before and after experimental exposure studies. 6. To provide an environmental research chamber to facilitate studies which require closely controlled and monitored environmental conditions. 7. To measure the radiologic response to airway injury caused by inhalation of aerosols and gases that are relevant to the rural and agricultural environment. 8. To develop methodology to non-invasively quantify airway caliber, determine airway wall thickness and to characterize the deposition of inhaled aerosols. 9. To enhance and promote training and the development of young investigators in the environmental health sciences. Outside advice was sought during the construction phase by Drs. Owen Moss and Beverly Cowen. Utilization of the chamber with balancing and validation began in June 1998.